This invention relates to a working vehicle with transverse system, which can be switched to a transverse travel mode.
Conventionally, working vehicles having a transverse system have primarily been found among large size conveyance vehicles and some loaders, and reach style electric vehicles as forklifts. In addition, there exists a side forklift with a mast and forks installed sideways in relation to the movement direction of the vehicle to allow the vehicle to handle elongated objects. However, there are no counter balance type forklifts that can move sideways and function like a side forklift in addition to such tasks as generally required. To realize this type of forklift, the front wheels or driving wheels are required to be steerable sideways.
Therefore, a conventional forklift 1, shown in FIG. 14, has a pair of right and left front wheels 3 (driving wheels) in a front part of a vehicle body 2, a pair of right and left rear wheels 4 in a rear part of the vehicle body 2, and a driver""s seat 5 on an upper front part of the vehicle body 2. A mast 6 capable of vertically extending and retracting is located at a front end of the vehicle body 2 to be able to tilt in a front-and-rear direction through a linking axle 7 extending in the direction of the vehicles"" width. Additionally, tilt cylinders 8 enabling the mast 6 to tilt forward and backward are placed between the vehicle body 2 and the mast 6.
The mast 6 comprises a pair of right and left outer frames 9 and a pair of right and left inner frames 10 capable of vertical movement by being guided by the outer frames 9. Disposed between the outer frames 9 and the inner frames 10 is a lift cylinder 11. Additionally, lift brackets 12 capable of vertical movement by being guided on the inner frames 10 are provided, and a pair of right and left forks 13 are secured to the lift brackets 12 through a pair of upper and lower finger bars.
The above mentioned driver""s seat 5 includes a seat 15, a steering wheel 16 located in front of the seat 15, and a headguard 19 disposed thereabove through front pipes 17 and rear pipes 18 which are erected on the vehicle body 2. A counterweight is located in the rear of the seat 15 on the vehicle body 2.
However, since the right and left front wheels 3 are driven in common by a same travel drive system, the above mentioned conventional forklift 1 cannot effect straight-sideways steering of the front wheels, thus being unable to move laterally.
The first objective of the present invention is to provide a working vehicle with a transverse system, in which driving front wheels can be steered straight sideways, and in the transverse travel mode, assisting in straight driving and attitude control such as changing a direction of a vehicle body (vehicle) can be achieved at a specified speed.
The second objective of the present invention is to provide a working vehicle with a transverse system, in which the driving front wheels can be steered straight sideways and angle adjustment of the front wheels can be made easily and precisely.
To achieve the first objective mentioned above, a working vehicle with a transverse system according to Claim 1 of the present invention comprises a pair of right and left front wheels and a pair of right and left rear wheels, respectively capable of steering, each of the pair of right and left front wheels being linked to a drive shaft on the travel drive system side, wherein each travel drive system is secured to a swing member capable of rotating around a vertical axis of the vehicle body, a means for rotating swing member is provided to allow a hydraulic operating device to rotate both swing members against each other, and a switching valve means is secured to a piping between a hydraulic pump and a working control valve, whereby the piping on a side to be switched by the switching valve means is connected to a control valve for the hydraulic operating device through a flow divider.
According to the above mentioned configuration of Claim 1 of this invention, the switching valve means during the normal travel mode is in a one-way switching condition, which will enable the full flow of pressure oil to be fed to the working control valve from the hydraulic pump. The hydraulically operating device is in the neutral position to steer the right and left front wheels in the front and rear directions. This type of working vehicle can drive both forward and backward and can operate various working functions through the working control valve.
Switching from the normal travel mode to the transverse travel mode is accomplished by switching a switching valve means into an opposite-way switching condition, thus full flow of pressure oil from the hydraulic pump can be fed directly to the flow divider which controls the flow to allow a specific amount of the flow to flow to the control valve for the hydraulic operating device.
This control valve for the hydraulically operating device controls only the pressure oil required for steering to allow oil to flow to the hydraulically operating device so as to operate the hydraulically operating device to rotate both swing members around a vertical axis, thereby to steer both front wheels through 90 degrees (steer straight sideways) in relation to the vehicle body. Because of the fact that both front wheels are respectively integrated with the travel drive system, the 90-degree steering can be achieved easily. Thus, after having steered both front wheels straight sideways, the front wheels are controllably rotated in either to-and-fro directions thereof by the travel drive system, whereby the working vehicle can travel laterally either to the right or left with respect to the vehicle body. At this time, the rear wheels are allowed for follow-up steering by means of a turning castor system or can be forcedly steered following the front wheels.
Further, when traveling transversely, or when the traveling mode is switched to the transverse traveling by steering for 90 degrees, the misalignment of straight-ahead driving due to poor road surface conditions and weight imbalance (load fluctuation between front and rear) can be corrected easily by operating the hydraulic operating device slightly to steer both front wheels facing inward or outward through a smaller angle. In addition, by steering both front wheels inward or outward, the direction of the working vehicle can be slightly changed during transverse traveling and the vehicle can also be turned during transverse traveling.
Since the flow divider is capable of controlling the flow to allow specific amount of flow to flow to the control valve for the hydraulic operating device irrespective of the flow rate of pressure oil from the hydraulic pump, steering both front wheels and posture control (correction of straightness) during transverse travel can be achieved and maintained at a specified speed easily and smoothly at all times.
To achieve the second objective mentioned above, the working vehicle with transverse system in Claim 2 of this invention, comprising a pair of right and left front wheels and a pair of right and left rear wheels mounted to a vehicle body, respectively to be capable of steering by 90 degrees, wherein each of the pair of right and left front wheels is linked to a drive shaft on the side of a travel drive system being secured to be capable of freely rotating around a vertical axis with respect to the vehicle body, wherein a rotating means is provided to have a turning cylinder which can be extended and contracted through a control valve by operating a transverse travel switch lever, a transverse control lever is secured separately from said transverse travel lever, to be capable of operating in a specified range, and there are provided a means for detecting a tilt location of said transverse travel lever and a means for detecting the steering angle of the front wheels, whereby outputted detected values from these detecting means are inputted to the valve controller to allow the control valve to be controlled according to an output from the valve controller.
According to the above mentioned configuration of claim 2 of this invention, when changing to a transverse travel operation, a transverse control lever, by inclining (tilting) slightly to one direction, contacts a turning cylinder slightly, and this enables both front wheels to steer outward (steered further) through a smaller angle (in the range of approximately 5 degrees). Therefore, the vehicle can travel transversely, correcting misalignment of straight-ahead driving due to poor road surface conditions and weight imbalance (fluctuation of load between front and rear) during transverse traveling. In addition, to travel to the turning direction in the transverse traveling condition with the rear end following up, the transverse control lever is further tilted to enable the front wheels to face outward even more. Also, to travel to the turning direction in the transverse traveling condition with the front end following up, the transverse control lever is tilted to the opposite side to slightly extend a turning cylinder, which enables both front wheels to face inward (in a slightly reversed state in steering) through a smaller angle (in the range of approximately 5 degrees).
Thus, when the turning cylinder is extended and contracted by tilting the transverse control lever, the detected values of both, a tilt location (tilt angle) of the transverse control lever is detected by the tilt location detecting means and a steering angle (steering volume) of the front wheels is detected by the steering angle detecting means, and the detected value signals from these detecting means are inputted into the valve controller. In addition, the valve controller confirms the difference between both detected signals, outputs the control signals to the control valve so that the steering angle of the front wheels corresponds (matches) to the tilt angle of the transverse control lever, thereby to extend and contract the turning cylinder. At this time, the transverse control lever can control the maximum tilting angle by being operated in the specified range.
Consequently, operating the transverse control lever affects the turning cylinder, enables the turning cylinder to move precisely during adjustment of the angle of the front wheels, thus performing the angle adjustments easily and precisely, and allows stopping at any desired angle.